Construction of a novel xanthine biosensor using zinc oxide (ZnO) and the biotemplate method for detection of fish freshness

Abstract

In the food industry, fish is a product that has a short shelf life, and xanthine has attracted significant attention as an indicator of the freshness of fish. In this study, we demonstrated a simple assay system containing zinc oxide (ZnO) and xanthine oxidase (XOD) for specific and quantitative detection of xanthine. ZnO nanomaterials have been successfully synthesized using a biotemplate method. The mechanism is based on the fluorescence quenching of ZnO via the electron transfer mechanism, which is caused by the hydrogen peroxide (H₂O₂) that is produced from the XOD-catalyzed oxidation of xanthine. By virtue of the specific response, the present assay allowed for the selective determination of xanthine in the range of 3.30 × 10⁻¹⁰–6.67 × 10⁻⁷ mol L⁻¹ and 2.67 × 10⁻⁶–2.67 × 10⁻⁴ mol L⁻¹ with a detection limit of 1.30 × 10⁻¹⁰ mol L⁻¹. The proposed method was successfully applied to the determination of xanthine in real fish samples with satisfactory results.